In the packaging of integrated circuits, package components, such as device dies and package substrates, are typically stacked through flip chip bonding. To protect the stacked package components, a molding compound is disposed surrounding the device die.
The conventional molding methods include compression molding and transfer molding. Compression molding may be used for over-molding. Since the compression molding cannot be used to fill the gaps between the stacked dies, the underfill needs to be dispensed in separate steps from the compression molding. On the other hand, transfer molding may be used to fill a molding underfill into the gap between, and over, the stacked package components. Accordingly, transfer molding may be used to dispense the underfill and the molding compound in the same step. Transfer molding, however, cannot be used on the packages including round wafers due to non-uniform dispensing of the molding compound.